Self-Defence against Non-state Actors: The Interaction between Self-Defence as a Primary Rule and Self-Defence as a Secondary Rule

This article examines the law of self-defence as applied to non-state attacks in light of the coalition air strikes against ISIL in Syria. It critiques the two current interpretations of the law of self-defence – one based on attribution and the other on the ‘unable or unwilling’ test – for failing to address adequately the security threat posed by non-state actors or for not addressing convincingly the legal issues arising from the fact that the self-defence action unfolds on the territory of another state. For this reason, it proposes an alternative framework which combines the primary rule of self-defence to justify the use of defensive force against non-state actors, with the secondary rule of self-defence to excuse the incidental breach of the territorial state's sovereignty.